/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.web.socket.sockjs.client;

import java.net.URI;
import java.util.UUID;

import org.springframework.lang.Nullable;
import org.springframework.util.IdGenerator;
import org.springframework.util.JdkIdGenerator;
import org.springframework.web.socket.sockjs.transport.TransportType;
import org.springframework.web.util.UriComponentsBuilder;

/**
 * Container for the base URL of a SockJS endpoint with additional helper methods
 * to derive related SockJS URLs as the {@link #getInfoUrl() info} URL and
 * {@link #getTransportUrl(TransportType) transport} URLs.
 *
 * @author Rossen Stoyanchev
 * @since 4.1
 */
public class SockJsUrlInfo {

    private static final IdGenerator idGenerator = new JdkIdGenerator();


    private final URI sockJsUrl;

    @Nullable
    private String serverId;

    @Nullable
    private String sessionId;

    @Nullable
    private UUID uuid;


    public SockJsUrlInfo(URI sockJsUrl) {
        this.sockJsUrl = sockJsUrl;
    }


    public URI getSockJsUrl() {
        return this.sockJsUrl;
    }

    public String getServerId() {
        if (this.serverId == null) {
            this.serverId = String.valueOf(Math.abs(getUuid().getMostSignificantBits()) % 1000);
        }
        return this.serverId;
    }

    public String getSessionId() {
        if (this.sessionId == null) {
            this.sessionId = getUuid().toString().replace("-", "");
        }
        return this.sessionId;
    }

    protected UUID getUuid() {
        if (this.uuid == null) {
            this.uuid = idGenerator.generateId();
        }
        return this.uuid;
    }

    public URI getInfoUrl() {
        return UriComponentsBuilder.fromUri(this.sockJsUrl)
                .scheme(getScheme(TransportType.XHR))
                .pathSegment("info")
                .build(true).toUri();
    }

    public URI getTransportUrl(TransportType transportType) {
        return UriComponentsBuilder.fromUri(this.sockJsUrl)
                .scheme(getScheme(transportType))
                .pathSegment(getServerId())
                .pathSegment(getSessionId())
                .pathSegment(transportType.toString())
                .build(true).toUri();
    }

    private String getScheme(TransportType transportType) {
        String scheme = this.sockJsUrl.getScheme();
        if (TransportType.WEBSOCKET.equals(transportType)) {
            if (!scheme.startsWith("ws")) {
                scheme = ("https".equals(scheme) ? "wss" : "ws");
            }
        } else {
            if (!scheme.startsWith("http")) {
                scheme = ("wss".equals(scheme) ? "https" : "http");
            }
        }
        return scheme;
    }


    @Override
    public String toString() {
        return "SockJsUrlInfo[url=" + this.sockJsUrl + "]";
    }

}
